This invention relates generally to a manhole closure, and specifically to a manhole closure that is readily installable in a conventional manhole opening, the improved closure including a two-way pressure relief valve.
Today's suburban sprawl has created a situation of more paved areas and less impervious areas for normal rainfall to dissipate into the soil. As a result, large amounts of surface runoff water seeps through the conventional sanitary sewer manhole cover vent holes. Thus, surface water entering the sewer system becomes contaminated and must be treated before disposal.
Waste treatment plants are designed with surplus capacity to handle peak load conditions. Depending on area location this capacity can be as high as 40% of the total plant capacity.
Not only will the present invention help keep one of our most precious natural resources from becoming contaminated, but it will also allow the existing waste treatment plants to use that portion of the plant for waste treatment that is normally provided to handle this infiltration. With the existing plants being able to treat a larger load of waste, less new facilities will be required.
To those familiar with the art of waste treatment, additional benefits will become apparent through less energy consumption, less equipment maintenance, less chance of detrimental environmental impact through a more positive treatment control.
The economical advantages of the instant invention in addition to the above benefits, is its long life expectancy. Since it is mounted below a conventional manhole cover, it may be primarily constructed of a plastic type material.
To install the invention, no change is required to the manhole, manhole frame, or manhole cover, the invention being adaptable to existing facilities as well as construction with no additional special tooling or skilled labor to accomplish this function.